JPH10169479A - Cylinder cut-off control device for multiple cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent worsening of an operating feeling at the time of reducing the number of cylinders by relatively enlarging the valve opening of a throttle valve interposed in an intake passage communicated with the operation continuous cylinder at the time of reducing the number of cylinders, and fully opening the valve opening of a throttle valve interposed in an intake passage communicated with the operation stop cylinder. SOLUTION: At the time of performing cylinder cut-off control by an ECU 10, elapsed time after the start of an engine, engine speed, the intake air quantity and cooling water temperature are detected, and when the elapsed time after the start of the engine exceeds the set time, whether warming-up of the engine is completed is judged from the cooling water temperature. When the engine is in a complete warming-up state, whether a present operating area is within a set area reducible in the number of operating cylinders is examined. In the affirmative case, fuel injection to operation stop object cylinders is stopped. The valve opening of a throttle valve 5a or 5b related to an operation continuous cylinder is made larger than that at the time of all cylinder operation, and a throttle valve 5b or 5a related to the operation stop cylinder is fully opened regardless of accelerator opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder rest control system for a multi-cylinder engine in which a throttle valve is provided for each cylinder or for a plurality of cylinders.

[0002]

2. Description of the Related Art Conventionally, a multi-cylinder engine employs a so-called cylinder-stop control technique for stopping the combustion of some cylinders and reducing the number of operating cylinders according to the operating state of the engine to improve fuel efficiency. This reduction in the number of operating cylinders can be easily realized, for example, in a multi-point injection multi-cylinder engine having an injector for each cylinder, by stopping fuel injection in the cylinder whose operation is stopped.
Since the pumping loss increases, an engine equipped with a mechanism for stopping the operation of the intake / exhaust valve of the cylinder whose operation is stopped has been put to practical use.

[0003] However, such an engine has problems such as a complicated valve operating system and an increase in cost.
For example, as proposed in Japanese Patent Application Laid-Open No. 3-145530, a throttle valve is provided in each intake passage for each cylinder to stop fuel injection of a cylinder whose operation is stopped, and to fully open the throttle valve of the corresponding cylinder. By doing so, it is possible to reduce pumping loss of the stopped cylinder.

[0004]

However, when performing cylinder stop control for stopping the operation of some of the cylinders, an unpleasant torque shock occurs because the engine torque sharply decreases from the operation of all cylinders. In addition, the shortage of the engine output torque with respect to the accelerator operation becomes remarkable, and the driver feels uncomfortable and the driving feeling deteriorates.

The present invention has been made in view of the above circumstances. When the number of operating cylinders is reduced, the pumping loss of the stopped cylinders is reduced, and the step of engine torque due to the reduced number of operating cylinders is reduced. It is an object of the present invention to provide a cylinder stop control device for a multi-cylinder engine, which can eliminate a feeling of strangeness and prevent a deterioration in driving feeling.

[0006]

According to the first aspect of the present invention,
In a cylinder rest control device for a multi-cylinder engine in which a throttle valve is interposed for each cylinder or for each of a plurality of cylinders, whether or not the number of operating cylinders can be reduced by stopping the operation of some cylinders based on the operating state of the engine And a valve for controlling the valve opening of a throttle valve interposed in the intake passage communicating with the cylinder to be operated in accordance with the accelerator opening during all-cylinder operation when the number of operating cylinders is reduced. A control means for making the opening larger than the opening and for fully opening the valve opening of the throttle valve interposed in the intake passage communicating with the operation stop cylinder regardless of the accelerator opening is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the cylinder rest determining means determines that the number of operating cylinders can be reduced when the engine is in a warm-up completed state and in a low load operation range. It is characterized by.

That is, it is determined whether the number of operating cylinders can be reduced by stopping the operation of some cylinders from the operating state of the engine, and it is determined that the number of operating cylinders can be reduced. When stopping, the valve opening of the throttle valve interposed in the intake passage communicating with the continuous operation cylinder is set to be larger than the valve opening controlled in accordance with the accelerator opening during full cylinder operation, and the cylinder is communicated with the stopped cylinder. The throttle valve installed in the intake passage is fully opened irrespective of the accelerator opening. In this case, desirably, it is determined that the number of operating cylinders can be reduced when the engine is in the warm-up completed state and in the low load operation range.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flowchart of a cylinder closing control routine, and FIG.
3 is a flowchart of a throttle opening calculation routine for a stopped cylinder, FIG. 3 is a flowchart of a throttle opening calculation routine for a constantly operated cylinder, FIG. 4 is a schematic configuration diagram of an engine control system, FIG. 5 is an explanatory diagram of a cylinder number reduction region,
FIG. 6 is an explanatory diagram showing a relationship between an accelerator opening and a throttle opening, and FIG. 7 is an explanatory diagram of a throttle opening reference table.

In FIG. 4, reference numeral 1 denotes an engine,
In the present embodiment, a horizontally opposed or V-type six-cylinder engine in which a cylinder block is divided into left and right banks 1a and 1b around a crankshaft is shown. Intake manifolds 2a and 2b communicating with the intake ports of the cylinders are attached to the cylinder heads of the left and right banks 1a and 1b of the engine 1, and the intake manifolds 2a and 2b for the left and right banks share a common intake pipe 3. Is communicated to.

Further, the left and right banks 1a,
An injector 4 is arranged for each cylinder immediately upstream of an intake port of each cylinder 1b, and a throttle valve 5 is provided at an upstream gathering portion of each of the intake manifolds 2a and 2b.
a, 5b are interposed. Each throttle valve 5a, 5b
Are provided with throttle actuators 6a and 6b, respectively, and the throttle opening is variably controlled for each bank.

The injectors 4 for each cylinder and the throttle actuators 6a and 6b connected to the throttle valves 5a and 5b for each bank are connected to an electronic control unit (ECU) 10 for electronically controlling the engine 1. Have been. The ECU 10 is mainly configured by a microcomputer, and is connected to various sensors and switches for detecting an engine operating state, such as an accelerator opening sensor 7 for detecting an amount of depression of an accelerator pedal (not shown). , The injector 4, the throttle actuators 6a and 6b,
Various actuators for engine control are connected.

The ECU 10 processes the signals from the sensors according to the control program stored in the memory to detect the engine operating state, and calculates the fuel injection amount, ignition timing, etc. according to the detected operating state. Perform engine control. In this engine control, electronic throttle control for controlling the throttle opening based on the accelerator opening (accelerator depression amount) and other engine operating conditions,
In addition, so-called cylinder-stop control, in which combustion in some of the cylinders is stopped in accordance with the operating state of the engine to bring it into a halt state in order to save energy, is also used.

Hereinafter, a process related to cylinder stop control by the ECU 10 will be described with reference to flowcharts of FIGS.

The cylinder closing control routine shown in FIG. 1 is a periodic processing routine executed at predetermined time intervals.
At 01, the elapsed time after the start of the engine, the engine speed, the intake air amount are calculated, and the cooling water temperature is detected to check the engine operating state. Next, the process proceeds to step S102, where it is determined whether or not the elapsed time after the start of the engine has exceeded the set time. If the elapsed time after the start of the engine is within the set time, the process proceeds to step S105 to clear the cylinder stop control execution flag. And exit the routine. In this case, cylinder stop control is not performed, and normal control according to the engine operating state is performed.

On the other hand, if the elapsed time after the start of the engine exceeds the set time, the process proceeds from step S102 to step S103, where the cooling water temperature detected in step S101 is compared with the set temperature to complete the warm-up of the engine. Check if it is. When the cooling water temperature is lower than the set temperature and the engine is in a cold state, and the warming-up is not completed, the routine exits from the step S103 through the above-described step S105, and the elapsed time after the engine start exceeds the set time exceeds the set time. When the water temperature exceeds the set temperature, that is, when the engine is in a completely warmed-up state, the process proceeds from step S103 to step S104, and whether the current operating region is within the set region where the number of operating cylinders can be reduced is determined. Find out what.

As shown in FIG. 5, the region in which the number of operating cylinders can be reduced is a low-load operation region specified by the engine speed and the intake air amount. If it is not within the range, the routine exits from the step S104 through the above-described step S105.
Proceeding to 06, the cylinder deactivation control execution flag is set to permit execution of cylinder deactivation control, and in step S107, fuel injection of the cylinder whose operation is to be stopped is stopped.

In the engine 1 of this embodiment, fuel injection to one cylinder, for example, each cylinder of the bank 1b is stopped, and the three cylinders of the bank 1b are simultaneously deactivated.
That is, the three cylinders of the bank 1a become the continuously operating cylinders that continue to operate irrespective of the execution of the cylinder deactivation control.
The three cylinders b are cylinders to be stopped. When stopping the fuel injection to the cylinder to be stopped, the ignition may be cut off at the same time.

In contrast to the cylinder rest control routine described above, the throttle opening for the cylinder whose operation is to be stopped is controlled by the throttle opening control routine of FIG. 2, and the throttle opening for the constantly operating cylinder is controlled by the throttle opening control routine of FIG. Controlled. In this embodiment, the throttle opening for the cylinder whose operation is to be stopped is the opening of the throttle valve 5b on the bank 1b side, and the throttle opening for the constantly operating cylinder is the opening of the throttle valve 5a on the bank 1a.

First, the throttle opening control routine for the cylinder whose operation is to be stopped in FIG. 2 will be described. In this routine, the accelerator opening is calculated from the output voltage of the accelerator opening sensor 7 in step S201, and in step S202, by referring to the cylinder closing control execution flag, it is determined whether or not the cylinder closing control is currently being performed. Find out.

When the cylinder-stop control flag is cleared and the cylinder-stop control is not performed, the process proceeds from step S202 to step S203, and the throttle opening is determined by referring to the table T1 based on the accelerator opening. When the cylinder-stop control flag is set and the cylinder-stop control is being performed, the process proceeds from step S202 to step S204, and the throttle opening is calculated with reference to the table T3.

The relationship between the throttle opening and the accelerator opening is set with a characteristic having a positive correlation between the accelerator opening of 100% and the throttle opening of 100% with respect to the operating cylinder as shown in FIG. In addition, the characteristic shown by c in FIG. 6, that is, the characteristic that the throttle is fully opened regardless of the accelerator opening degree is set for the cylinder whose operation is stopped.

Accordingly, as shown in FIG. 7, a table T1 storing the throttle opening corresponding to the accelerator opening based on the characteristic a, and a table storing the throttle opening corresponding to the accelerator opening based on the characteristic c. T3,
The throttle opening is selected according to whether or not the cylinder deactivation control is being performed, and the throttle opening is calculated.

When the throttle opening is calculated in step S203 or S204, step S2
At 05, a drive signal corresponding to the calculated throttle opening is output to the throttle actuator 6b connected to the throttle valve 5b on the bank 1b side, and the routine exits.

Thus, not only can the number of operating cylinders be reduced when the load is low, and the equal capacity of the cylinders that continue to operate is improved, but also the pumping loss can be reduced because the throttle opening of the cylinder that is not operating is fully opened. And a great improvement in fuel efficiency can be realized.

On the other hand, in the throttle opening control routine for the continuously operating cylinder shown in FIG. 3, similarly, the accelerator opening is calculated from the output voltage of the accelerator opening sensor 7 in step S301, and the cylinder closing control execution flag is determined in step S302. See
It is checked whether or not the cylinder stop control is currently performed.

When the cylinder-stop control flag is cleared and the cylinder-stop control is not performed, the process proceeds from step S302 to step S303, and the throttle opening is performed by referring to the above-described table T1 based on the accelerator opening. When the cylinder stoppage control flag is set and cylinder stoppage control is being performed, step S302 is performed.
Proceeding to S304, the throttle opening is calculated with reference to the table T2. Although the table T2 has a positive correlation with the accelerator opening as shown by b in FIG. 6, compared to the characteristics of the above-described table T1 shown by a in FIG. Data of a characteristic that results in a larger throttle opening is stored.

When the throttle opening is calculated in step S303 or step S304, step S3
At 05, a drive signal corresponding to the calculated throttle opening is output to the throttle actuator 6a connected to the throttle valve 5a on the bank 1a side, and the routine exits.

That is, when the cylinder deactivation control is not performed, the throttle opening of the bank 1a, which is the constantly operating cylinder, and the throttle opening of the bank 1b, which is the cylinder whose operation is to be stopped, are both predetermined. The throttle opening is the same as the accelerator opening, but when cylinder closing control is performed, the throttle opening on the bank 1b side, which is the cylinder whose operation is to be stopped, is fully opened regardless of the accelerator opening. The throttle opening on the bank 1a side, which is the cylinder side, is a larger throttle opening than during the normal control in which the cylinder stop control is not performed.

Accordingly, when the number of operating cylinders is reduced by performing cylinder deactivation control, the step of engine torque can be reduced as long as the effect of improving fuel efficiency is not impaired, and the driver's feeling of insufficient torque with respect to accelerator operation can be reduced. It is possible to eliminate the driver's discomfort.

In the present embodiment, an example has been described in which a throttle valve is interposed in the intake manifold assembly of each bank divided into left and right, and the cylinders of one bank are stopped in the entire cylinder group. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to, for example, an engine provided with a throttle valve that can be independently controlled in each intake passage of a plurality of cylinders.

[0032]

As described above, according to the present invention, it is determined whether or not the number of operating cylinders can be reduced by stopping the operation of some of the cylinders from the operating state of the engine, and the number of operating cylinders can be reduced. When the operation of some cylinders is stopped by judging, the valve opening that controls the valve opening of the throttle valve interposed in the intake passage communicating with the cylinder that is in operation according to the accelerator opening during all cylinder operation To reduce the pumping loss of the stopped cylinders and reduce the number of operating cylinders to fully open the throttle valve interposed in the intake passage communicating with the stopped cylinder regardless of the accelerator opening. Thus, it is possible to prevent the occurrence of torque shock by reducing the level difference of the engine torque, and to eliminate the feeling of insufficient engine output torque due to the accelerator operation. Therefore, excellent effects can be obtained such that the driver's feeling of discomfort when the number of driving cylinders is reduced can be eliminated and the driving feeling can be prevented from deteriorating.

[Brief description of the drawings]

FIG. 1 is a flowchart of a cylinder closing control routine.

FIG. 2 is a flowchart of a throttle opening calculation routine for a cylinder to be stopped;

FIG. 3 is a flowchart of a throttle opening calculation routine for a constantly operating cylinder.

FIG. 4 is a schematic configuration diagram of an engine control system.

FIG. 5 is an explanatory diagram of a cylinder number reduction region.

FIG. 6 is an explanatory diagram showing a relationship between an accelerator opening and a throttle opening;

FIG. 7 is an explanatory diagram of a throttle opening reference table;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 5a, 5b ... Throttle valve 10 ... ECU

Claims (2)

[Claims] A multi-cylinder engine with a throttle valve interposed for each cylinder or for each of a plurality of cylinders is provided with a cylinder-stop control system. Cylinder determination means for determining whether or not the number of operating cylinders can be reduced.When the number of operating cylinders is reduced, the valve opening of the throttle valve interposed in the intake passage communicating with the continuation cylinder is set to the accelerator opening during all cylinder operation. Control means for controlling the valve opening to be greater than the valve opening to be controlled in response to the opening of the throttle valve interposed in the intake passage communicating with the stopped cylinder, regardless of the accelerator opening. Cylinder rest controller for multi-cylinder engine. 2. The multi-cylinder engine according to claim 1, wherein said cylinder deactivation determining means determines that the number of operating cylinders can be reduced when the engine is in a warm-up completed state and in a low load operation range. Tube control device.